A typical smart key system operates as follows. Upon opening a door of a vehicle by use of a FOB key, a Personal Identification Card Electronic Control Unit (PIC ECU) wakes up a Mechatronic Steering Column Lock (MSCL) controller. When all the doors of the vehicle are subsequently closed, the PIC ECU operates an interior antenna and checks whether a valid FOB key exists inside the vehicle. After authentication of validity of the FOB key and a user pushes a knob of a steering column lock device, a knob-push switch detects this and transmits it to the PIC ECU. The PIC ECU transmits a command directing the MSCL controller to release a locked state. Next, the MSCL controller supplies electricity to a solenoid which locks the knob, so that the knob is caused to be rotatable, thereby making starting of the vehicle possible.